Method of sealing tubing

ABSTRACT

A METHOD OF MAINTAINING THE INTERIOR OF STRAIGHT LENGTHS OF COPPER TUBING USED IN AIR CONDITIONING AND REFRIGERATION SYSTEMS IN CLEAN CONDITION WHICH COMPRISES THOROUGHLY CLEANING THE INSIDE, DRYING THE TUBE, PURGING THE TUBE WITH AN INERT GAS SUCH AS NITROGEN AND SEALING THE ENDS BY PRESSURE-RESISTANT RESILIENT DEFORMABLE PLUGS INSERTED THEREIN TO ENTRAP THE GAS AT SUPER ATMOSPHERIC PRESSURE. A SPECIFIC PLUG CONSTRUCTION IS ALSO DISCLOSED.

Aug. 20, 1974 J, FUES'LEW EI'AL Re. 28,124

METHOD OF SEALING TUBING Original Filed Aug. 14, 1962 United StatesPatent 28,124 METHOD OF SEALING TUBING John R. Fueslein, Jeddo, Mich.,and Edward C. Roper, deceased, late of Springdale, Conn., by MuellerBrass (10., Port Huron, Mich., assignee Original No. 3,274,747, datedSept. 27, 1966, Ser. No.

389,597, Aug. 14, 1964, which is a division of application Ser. No.216,841, Aug. 14, 1962, now Patent No. 3,200,984. Application forreissue Feb. 9, 1973, Ser. No. 331,316

Int. Cl. B671) I/04 US. CI. 53-22 R 3 Claims Matter enclosed in heavybrackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE A method of maintaining the interior ofstraight lengths of copper tubing used in air conditioning andrefrigeration systems in clean condition which comprises thoroughlycleaning the inside, drying the tube, purging the tube with an inert gassuch as nitrogen and sealing the ends by pressure-resistant resilientdeformable plugs inserted therein to entrap the gas at super atmosphericpressure. A specific plug c nstruction is also disclosed.

The present invention broadly relates to sealing means for tubularmembers and, more particularly, to an improved sealing plug particularlyadapted to be employed in conjunction with tubular members such asmetallic tubing and to an improved method of protecting the interior ofsuch tubular members from contamination during transit and storage. Thisapplication is a division of the applicants copending application,Serial No. 216,841, filed August 14, 1962, now Patent No. 3,200,984issued August 17, 1965.

Apparatus of the general type employing tubular members in a fluidsystem, such as air conditioning and refrigeration apparatus, is inwidespread industrial, commercial and residential use, and in apparatusof this general type it is important that the components of the fluidsystem, including the tubular members, be maintained in a substantiallyclean condition free from undesirable deposits, particles anddeleterious contaminating fluids such as moisture prior to the assemblyof the system in order to prevent the introduction of such foreignmatter into the fluid system as may cause malfunction or erraticoperation of the system. Although heretofore it has been the practice tothoroughly clean the tubular members at the time they are manufactured,a continuing and heretofore unresolved problem has been encountered as aresult of the introduction of contaminating materials into the tubularmembers during transit and while such members are stored prior to thetime they are assembled in the air conditioning or refrigeration system.Consequently, it has been necessary heretofore to again thoroughly cleanthe interior surfaces of the tubular members and to remove moisturetherefrom at the site of the final assembly of the system with aresultant increase in the cost of the manufacturing and assembly of theapparatus.

It is accordingly a primary object of the present invention to providean improved sealing plug for tubular members and an improved method ofsealing such members after cleaning whereby the interiors thereof aremaintained in a substantially clean condition for indefinite periods oftime during shipment and storage prior to use.

Another object of the present invention is to provide an improvedsealing plug construction of a resilient and Reissued Aug. 20, 1974deformable nature which can be simply and quickly removably installed inthe ends of tubular members providing a pressure type fiuid seal whichserves to prevent the entrance of undesirable contaminating materialsinto the interior of the tubular member.

A further object of the present invention is to provide an improvedsealing plug construction which incorporates novel sealing means whichon application of pressure thereto promotes more perfect sealing of theplug against the wall surfaces of a bore in which it is removablydisposed.

Still another object of the present invention is to provide a uniquemethod of maintaining the interior of tubular members in anuncontaminated state for indefinite periods of time thereby avoiding thenecessity of cleaning such tubing at the job site prior to installation.

Yet another object of the present invention is to provide a method ofmaintaining the interior of tubular articles in a clean, uncontaminatedstate for indefinite periods of time enabling the article to beinitially cleaned in effective cleaning apparatus at the point ofmanufacture and in which clean condition the interior of the tube ismaintained until its use.

The above as well as other objects and advantages of the presentinvention will become apparent from the following description, theappended claims and the accompanying drawings, wherein:

FIGURE 1 is a side elevation View of an improved sealing plug embodyingthe present invention, with portions thereof shown in section;

FIG. 2 is an end elevation view of the sealing plug shown in FIG. 1 asviewed in the direction of the arrow indicated at 2, and

FIG. 3 is a longitudinal, sectional view of the sealing plug shown inFIG. 1, showing the same disposed within the interior of one end of atubular member and in a deformed sealing condition against the innersurfaces thereof.

Referring now in detail to the drawings, a unitary sealing plug,generally designated 10, is illustrated embodying the preferred featurescomprising the present invention. The plug 10 includes a body portion 12having an exterior wall which is of a substantially cylindricalconfiguration. In the specific embodiment shown in the drawings theperipheral surface of the sealing plug is provided with a slight,substantially uniform taper throughout the length thereof. The provisionof a slight taper on the peripheral surface of the sealing plug is notnecessary to achieve satisfactory sealing characteristics of the sealingplug but is sometimes provided to facilitate extraction of the plug froma mold or die in which it is formed. The plug 10 also includes a conicalend wall 14 which is integral with the smaller end of the body portion12, the apex of the cone projecting axially outwardly from the bodyportion and substantially coinciding with the longitudinal axis of thebody portion. At least one and preferably a plurality of spaced grooves20 are provided around the periphery of the body portion 12 adjacent theend wall 14 as best seen in FIGURE 1. The grooves 20 are spacedlongitudinally of the body portion and form sealing beads or ribs 22,the outer surfaces of the sealing ribs preferably having a convexconfiguration facilitating compression thereof in a manner as shown inFIGURE 3 so as to assure intimate contact with the inner surface of abore when the sealing plug is inserted therein.

The body portion 12, including the ribs 22, and the conical end wall 14are composed of a resilient deformable material enabling flexing anddeformation of the sealing plug when it is inserted within a circularbore such as a bore 16 of a tuble 18 as shown FIGURE 3. Materialspossessing the requisite resiliency and flexibility include natural andsynthetic rubbers, as well as synthetic plastic materials such aspolymers and copolymers of vinyl base plastics, polyethylene,polypropylene and the like. One plastic material which has been foundsuitable comprises a vinyl plastic avalable from the B. F. Goodrich Chemical Co. When natural or synthetic rubber is employed, it is preferredthat it be substantially devoid of any free sulfur which has a tendencyto attack the surfaces of copper or copper alloy tubing against whichthe sealing plug may be disposed. The rubber is also preferably of theself sealing type to enable puncture and self sealing of the plug duringpressurization of the interior of the tubing in a manner subsequently tobe described. A rubber formulation which has been found eminentlysatisfactory for this purpose preferably has a durometer reading ofabout 65 to about 75.

The resiliency and deformability of such materials enables the sealingplug to be inserted within a circular bore in tight frictional contactwith the inner surface thereof facilitating frictional engagementthereof with such inner surface and providing a substantially fluidtypeseal therebetween. Moreover, the resilient characteristics of thematerial enables the plug to conform to slight surface irregularitieswhich may exist along the surface of the bore assuring intimate sealingcontact of the surfaces of the plug with the surface of the bore.

The outer substantially cylindrical surface of the body portion 12 ashereinbefore mentioned, may be provided with a slight longitudinal taperwhich facilitates removal or extraction of the sealing plug from a moldor die and also facilitate wedging and compression of the sealing plugwhen it is inserted in a bore to be sealed. Conventionally, when a taperis employed it is preferred that it extend for substantially the entirelength of the sealing plug. The angle of such a taper is relativelysmall and generally tapers of about 1' provide for simple extraction ofthe plug from a die and provide for satisfactory sealing action.

The oversized diameter of the peripheral surface of the sealing plugrelative to the bore in which it is inserted effects deformation of thebody of the plug as shown in FIGURE 3 assuring intimate surface contacttherewith. For most deformable resilient materials sealing plugs havinga peripheral diameter of about greater than the diameter of the bore tobe sealed provides sufficient compression of the plug to maintain firmfrictional engagement thereof within the bore sufficient to withstandthe outward pressure of a fluid within the tubular member being sealed.

Sealing plugs constructed in accordance with the embodiment as shown inthe drawing, for example, employed for sealing the ends of tubing andcomposed of a vinyl plastic has been found eminently satisfactory forsealing tubing having inside diameters ranging from .315 inch to 1.505inches wherein the outer diameter of the body of the sealing plug rangedfrom about .035 to about .045 of an inch greater than the diameter ofthe bore to be sealed.

The engaging relationship of the sealing ribs 22 with the inner surfaceof the bore is further promoted by the convex configuration of the endwall 14 which projects axially and outwardly of the body 12. The convex,longitudinally protruding configuration of the end wall 14 is effectiveto increase the radial bearing pressure of the sealing ribs 22 andforward end of the body portion 12 against the inner surface of a borein response to endwise pressure exerted against the end wall causing itto deflect inwardly from the position as shown in phantom in FIG. 3 tothe position shown in solid lines. In the specific embodiment of thesealing plug 10 shown in the drawings, the end Wall 14 is of arelatively flat symmetrical conical configuration which, upon theapplication of pressure to the outer surface thereof, has a tendency toflatten, exerting increased radial bearing pressure of the sealing ribsagainst the inner surface of the bore. By virtue of this novelconstruction, increases in the pressure of the fluid contained within anarticle sealed promote a more effective of the sealing plug in the bore.

To enhance the deformability characteristics of the body 12 of thesealing plug in addition to the axial flexing characteristics of the endwall 14 in response to pressure applied thereto, the sealing plug 10 ispreferably provided with an axially extending cavity 24 extendinginwardly from the end remote from the end wall 14 as shown in thedrawings forming therewith a generally cup-shaped plug as defined by anannular wall 26 and the end wall 14. The inner surface 28 of the endwall 14 is preferably spaced from the outer surface of the end wall 14 adistance corresponding substantially to the thickness of the cylindricalwall 26 of the body. The particular thickness of the annular wall 26 andthe end wall 14 can be varied consistent with considerations of theparticular flexing and resiliency characteristics of the material ofwhich the sealing plug is comprised to provide the necessary strengthand deformability characteristics to provide secure frictionalengagement of the periphery of the sealing plug with the surface of thebore. Conventionally, a thickness of the end wall 14 and the annularwall 26 of the body when made of a vinyl plastic corresponding to about20% of the outer diameter of the plug have provided exceptionallysatisfactory sealing characteristics over a broad range of tubingdiameters and internal pressures.

It will be apparent from the foregoing that the sealing plug 10 can beemployed for providing a substantially fluid-type seal in circular boresand is particularly satisfactory for sealing the ends of tubing whichhas been preliminarily cleaned and filled with an inert gas inaccordance with the method comprising the present invention. Inaccordance with this method, tubing such as the tube 18 fragmentarilyshown in FIG. 3 either of a straight length or of a particular curved orbent preformed configuration is subjected to a cleaning operationwhereby undesirable foreign matter, deposits and other contaminants suchas oxidation scale, oils and lubricants employed during the manufactureof the tubing, dust, dirt and the like are removed from the interiorsurfaces of the bore 16 rendering the tubing in a commerciallyacceptable of cleanliness.

Any one of a number of well-known mechanical and chemical cleaningtechniques or combinations can be employed for removing such undesirabledeposits from the interior walls of the tubing. For example, suitablechemical cleaning steps such as an acid wash followed by a water rinsecan be satisfactorily employed for removing undesirable deposits fromthe interior of the tubing. After the chemical treatment or othermechanical or combination treatments, the interior of the tubing isdried and the air and any residual moisture are thereafter purgedtherefrom by passing a stream of a relatively dry inert gas such asnitrogen, for example, through the tubing.

One end of the substantially dry purged tubing containing inert gas isthereafter sealed employing a sealing plug of the type shown in thedrawings and further pressurization of the interior of the tubing ismade in order that the pressure of the inert gas exceeds the atmosphericpressure to which the tubing will be exposed during shipment andsubsequent storage. A positive pressure within the interior of thetubing is preferred so as to prevent any inward flow of air, dust andmoisture into the interior thereof.

Pressurization of the interior of the cleaned and purged tubing with anyone of a number of substantially dry, inert gases or mixtures thereofcan be suitably accomplished by placing the entire tube or one open endthereof in a sealed pressure chamber containing the inert gas andthereafter inserting a sealing plug in the open end or ends of thetubing entrapping the pressurized gas in the interior of the tubing.Alternatively, and a preferred method of pressurizing the interior ofthe cleaned tubing comprises sealing the open ends of the purged tubingwith a sealing plug of a resilient material, such as rubber, forexample, having self-sealing characteristics. The interior of the sealedtubing is thereafter pressurized by inserting and piercing one of thesealing plugs with a hollow or tubular needle through which thepressurized inert gas is pumped into the interior of the tubing untilthe desired positive pressure is attained. The tubular needle isthereafter Withdrawn and the self-sealing characteristics of thematerial of which the sealing plug is comprised seals the puncture inthe plug retaining the pressurized inert gas in the interior of thetubing. In either case, a pressurized, hermetically sealed unit isprovided which remains in such condition for substantially prolongedperiods of time.

It will be apparent from the foregoing that the method comprising thepresent invention and the novel sealing plug as herein disclosed anddescribed, provides an economical and effective method for maintainingthe interior of hollow articles and particularly tubing in a high stateof cleanliness for prolonged periods of time preventing oxidation attackor deposition of foreign matter on the interior surfaces thereof andsimultaneously preventing contamination of the protective fluidatmosphere contained within the article.

While it will be apparent that the preferred embodiments hereinillustrated are well calculated to fulfill the objects above stated, itwill be appreciated that the invention is susceptible to modification,variation and change without departing from the proper scope or fairmeaning of the subjoined claims.

What is claimed is:

[1. A method for maintaining the interior of tubular members devoid ofcontamination and deposits for prolonged periods of time which comprisesthe steps of cleaning the interior of the members to remove undersirabledeposits from the inner surfaces thereof, purging the interior of thecleaned said members with a substantially moisture-free inert fluid, andthereafter sealing said inert fluid in the interior of said members] [2.A method for maintaining the interior of tubing devoid of contaminationand undesirable deposits for prolonged periods of time which comprisesthe steps of cleaning the interior surfaces of the tubing to removeundesirable deposits therefrom, drying and purging the interior of thecleaned said tubing, introducing a substantially moisture-free inertfluid into the tubing, and thereafter sealing said inert fluid withinthe interior of said tubing] 3. A method for maintaining the interior ofstraight lengths of copper tubing for air conditioning and refrigerationsystems having inside diameters of at least .315 inch and smoothunthreaded inner and outer surfaces throughout their entire lengthdevoid of contamination and moisture for prolonged periods of time whichcomprises the steps of cleaning the interior of the tubing to removeforeign matter including oils and lubricants used during manufacturefrom the inner surfaces thereof, drying the interior of said tubing toremove substantially all of the moisture therefrom, purging the interiorof the dried and cleaned said tubing with a substantially moisture-freeinert [fluid] gas such as nitrogen, forming a pair of removablepressure-resistant plugs of resilient deformable material for eachlength of tubing, each plug being formed so that at least a substantialportion of its outer surface is circular and has an unstressed outerdiameter slightly greater than the inside tubing diameter, insertingsaid plugs in the opposite ends of said length of tubing by exertingforces which cause the plugs to be deformed and forced into the ends ofthe tubing, whereby the resilient nature of the plug material will causeit to be pressed radially outwardly against the tubing bore with asealing action, continuing said plug inserting forces until at leastsubstantial portions of said plugs have entered said tubing butsufiicient outer end portions still remain accessible to facilitatelater removal of the plugs in the field, and creating a positivepressure of said inert gas within said cleaned, dried and purged tubingwhereby said inserted plugs will entrap said gas at a pressure exceedingthe atmospheric pressure to which the tubing will be exposed duringshipment and subsequent storage.

[4. A method for maintaining the interior of refrigeration and airconditioning tubing devoid of contamination and moisture for prolongedperiods of time which comprises the steps of cleaning the interior ofthe tubing to remove foreign matter from the inner surfaces thereof,drying the interior of the cleaned said tubing, pressurizing theinterior of said tubing with an inert fluid to a pressure aboveatmospheric pressure, and thereafter sealing said pressurized inertfluid within the interior of said tubing] 5. The method according toclaim 3, in which pressurization of the interior of the cleaned, driedand purged tubing is accomplished by placing at least one open endthereof in a sealed pressure chamber containing the inert gas andthereafter inserting a sealing plug in the open end or ends of thetubing entrapping the pressurized gas in the interior of the tubing.

6. The method according to claim 3, in which pressurization of theinterior of the cleaned, dried and purged tubing comprises the steps ofsealing the open ends of the purged tubing with said sealing plugs, thematerial of said sealing plugs having self-sealing characteristics, andthereafter inserting and piercing one of the sealing plugs with a hollowneedle through which the pressurized inert gas is pumped into theinterior of the tubing until the desired positive pressure is attained,after which the tubular needle is withdrawn and the self-sealingcharacteristics of the material of which the sealing plug is comprisedseals the punctured plug retaining the pressurized inert gas in theinterior of the tubing.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 1,916,474 7/ 1933 French et a1. 148-203 2,897,6428/1959 Jones et a1 53-7 2,670,871 3/ 1954 Spiess et al 22024 2,079,0555/ 1937 Ward 53-88 2,319,234 5/ 1943 Hothersall 53-43 2,714,447 8/ 1955Cardes 206-46 2,746,632 5/ 1956 Bramming 215-52 3,021,975 2/1962Sarafinas 215-52 X 3,080,269 3/ 1963 Pollock et al 156294 X 3,115,01012/1963 Collier 53-7 X TRAVIS S. MOGEHEE, Primary Examiner US. Cl. X.R.5'3--7, 43

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NC. bated20,

In nt John R. Fueslein et 3,1

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 5, line 64, after the comma insert [and thereafter sealing theends of saidtubing to entrap said inert fluid therein at a pressuregreater than the pressure of the surrounding atmosphere] Signed andsealed this 26th day of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. c. MARSHALL DANN Arresting Officer Commissioner ofPatents po'1o5ouo'es) USCOMM-DC 60316-P09 ILST GOVERNMENT PRINTING OFFCC1." 0-356-33.

